There is a continual emphasis on improved high temperature characteristics for resinous materials and for curing agents which will improve the characteristics of already existing polymeric materials.
U.S. Pat. No. 3,182,073 describes trimellitic anhydride derivatives useful as curing agents for various resinous materials such as polyesters, epoxy resins and the like and also as substituents for preparing polyimides. U.S. Pat. No. 3,182,073 does not disclose the aromatic trisanhydrides of the present invention.
Accordingly, it is an object of the present invention to provide aromatic trisanhydrides which are useful as curing agents for epoxy resins, phenolics, polyesters and other oligomers and polymers containing hydroxyl groups and as monomer for the synthesis of star-branched polyimide-ester and polyimide-amides with radial symmetry.
It is a further object of the present invention to provide polymeric materials exhibiting high thermo-oxidative stability, Tg, toughness and mechanical strength.
Various other objects and advantages of this invention will become apparent from the following description thereof.